Low peak pressure body support

ABSTRACT

A body support such as a mattress is provided formed of a top layer, an intermediate layer and a base layer. Optional side supports are also provided. Each of these layers and optional side supports are formed of different polyurethane and/or latex foam compositions. Maximum and average peak pressures are minimized by having the intermediate layer of the mattress or other body support be formed of high resilience foam, such as foam with between forty-five and sixty-five percent resilience factor. This intermediate layer is also provided with a greater density than typical prior art body supports, with a density of between 2.5 and 3.5 pounds per cubic foot.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit under Title 35, United States Code§119(e) of U.S. Provisional Application No. 61/896,299 filed on Oct. 28,2013.

FIELD OF THE INVENTION

The following invention relates to mattresses and other cushions forbeds, chairs and other structures upon which at least portions of a bodyare able to rest. More particularly, this invention relates tomattresses and other cushions formed of multiple layers of polyurethaneand/or latex foam having characteristics which minimize peak pressurewhen a user rests upon the mattress.

BACKGROUND OF THE INVENTION

Mattresses, seat cushions and other body supports are provided both forcomfort and therapeutic purposes. Such supports are generally referredto herein as mattresses even when they are utilized as a seat cushion orother body support on a structure other than a bed. One form of mattressis formed of a mass of one or more layers of foam. Materials from whichsuch foam mattresses are formed include polyurethane foam, latex foam,or combinations of polyurethane and latex foam, or other foams withsimilar functional characteristics. Examples of such prior artmattresses include those disclosed in U.S. Pat. Nos. 8,037,562 and8,291,535, incorporated herein by reference in their entireties.

In various prior art mattress embodiments, such as those disclosed inthe above referenced patents, multiple horizontal layers of foam arebonded together in a vertical stack. The different layers exhibitparticular densities and particular layer thicknesses to optimizeperformance. When optimizing performance, at least two measures ofperformance can be evaluated, including average pressure and maximumpressure. In particular, testing can be performed where apparatuses ofknown standard weight simulating a human body or other object are placedupon the mattress and pressure readings between the mattress and thebody simulator or other object are measured. Where no pressure ismeasured, such readings are generally ignored. Where a pressure readingis measured, it can be mapped to the point where the reading took placeand display a pressure magnitude. “Average pressure” is the average ofall non-zero pressures that are sensed and “peak pressure” is thehighest magnitude pressure sensed.

Both for comfort and therapeutic purposes it is desirable to minimizeaverage pressure and to minimize peak pressure. If the average pressureis lower, weight of the person or other object is distributed over alarger portion of the mattress so that high pressure in any particularpoints can be minimized. Peak pressure is another measure of the degreeto which the mattress effectively avoids “pressure points” where higherpressure is measured. Such pressure points can be sufficiently high tocut off or restrict capillary blood flow, pinch nerves, or otherwiseprovide uncomfortable and medically undesirable conditions. Suchconditions include pressure sores, also known as “bed sores.” Also, whena wound is healing lower pressure measurements generally indicate a moreconducive environment for wound healing.

SUMMARY OF THE INVENTION

With this invention modifications to prior art mattresses such as thosedisclosed above have resulted in drastically improved peak pressures anddrastically improved average pressures through construction of a uniquemulti-layer foam mattress as disclosed herein. Details of the mattressof this invention are similar to those disclosed in the above-referencedpatents except where specifically identified herein.

First, the mattress of this invention utilizes a high resilience foamfor the intermediate layer (the intermediate layer being the layerbetween the top layer and the bottom layer). In particular, theintermediate layer has a high resilience foam (such as that defined byASTM D3770) with a resilience factor of preferably substantially aboutfifty-five percent while still within the same twenty-five tothirty-five IFD (Indentation Force Deflection) range. High performanceis also expected with high resilience foam with a resilience factor offorty-five to sixty five percent. Prior art foam mattresses, such asthose disclosed above, utilize high density non-high resilience foam.

Second, the intermediate layer is provided with a density between 2.5pounds per cubic foot and 3.5 pounds per cubic foot. This intermediatelayer density is greater than the density of the prior art foammattresses identified above. Third, a ratio of layer thicknesses hasbeen modified to optimize mattress performance. In particular, the toplayer and intermediate layer are provided with substantially the samethickness and the base layer has a thickness that is fifty percent ofthe intermediate layer thickness. This base layer has a tolerance rangeof plus or minus 0.5 to 1 inch. A formula which establishes thisrelationship includes:

A=B=2C

Where A is the thickness of the top layer, B is the thickness of theintermediate layer and C is the thickness of the base layer. The baselayer has a tolerance of plus or minus 0.5 to 1 inch. The layers haveprogressively higher IFD (Indentation Force Deflection) from top tobottom as is known with prior art mattresses.

One potential modification to the layer configurations disclosed hereinis to have the base layer or other higher density layer extend up atperimeter edges of the mattress, partially or all of the way to theupper surface of the mattress, or even higher than the upper surface inthe form of a “fall guard.” Such a stiff perimeter wall can tend to keepan individual located upon the mattress from too easily rolling off ofthe mattress.

OBJECTS OF THE INVENTION

Accordingly, a primary object of the present invention is to provide amattress which minimizes both average peak pressure and maximum peakpressure.

Another object of the present invention is to provide a mattress whichminimizes the occurrence of bed sores and assists in the remedying ofbed sores which already exist.

Another object of the present invention is to provide a mattress, seatcushion or other bodily support which is comfortable for a user.

Another object of the present invention is to provide a bodily supportwhich helps to keep a user from falling off of the support.

Other further objects of the present invention will become apparent froma careful reading of the included drawing figures, the claims anddetailed description of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the mattress of this invention accordingto a first embodiment and showing the various layers bonded together toform the mattress.

FIG. 2 is a side elevation view of that which is shown in FIG. 1.

FIG. 3 is an end elevation view of that which is shown in FIG. 1.

FIG. 4 is a perspective view similar to that which is shown in FIG. 1,but for an alternative embodiment including side supports thereon

FIG. 5 is a side elevation view of that which is shown in FIG. 4, withdashed lines illustrating hidden layers.

FIG. 6 is a side elevation full sectional view of that which is shown inFIG. 4.

FIG. 7 is an end elevation view of that which is shown in FIG. 4, withdashed lines revealing layers within the mattress of FIG. 4.

FIG. 8 is an exploded parts view of that which is shown in FIG. 4 andwith a dashed line illustrating a crease line about which the mattressis configured to more effectively bend.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the drawings, wherein like reference numerals representlike parts throughout the various drawing figures, reference numeral 10is directed to a mattress or other body support (FIG. 1) which is madeup of multiple layers of foam and which minimizes pressure pointsexperienced by a user resting upon the mattress 10.

In essence, and with particular reference to FIGS. 1-3, basic details ofthe mattress 10 are described, according to this first embodiment. Themattress 10 is formed of multiple layers of polyurethane and/or latexfoam. The layers include a top layer 20 resting upon an intermediatelayer 30 which is located upon a base layer 40. Each layer 20, 30, 40 issimilar in horizontal surface area. The top layer 20 and intermediatelayer 30 are similar in thickness. The base layer 40 is half of thethickness of the top layer 20 or intermediate layer 30 in this firstembodiment with a tolerance of 0.5 to 1.0 inch. Each layer 20, 30, 40 isformed of a homogeneous foam material such as a polyurethane foam orlatex foam. These layers 20, 30, 40 are provided with particulardensities and particular indentation force deflection values, andselected resilience factors to keep pressure points to a minimum.

More specifically, and with continuing reference to FIGS. 1-3, specificdetails of the various layers 20, 30, 40 of the mattress 10 aredescribed, according to this first embodiment. The top layer 20 is aplanar unitary mass formed of a polyurethane or latex foam. Preferably,this foam is homogeneous within the top layer 20.

The top layer 20 has a thickness extending between a planar top surface22 and a planar undersurface 24. The thickness is preferably uniform andin this first embodiment is exemplified with a thickness of three inchesbetween the top surface 22 and undersurface 24. A perimeter 26 extendsbetween the top surface 22 and the undersurface 24 and provides sidesand ends for the top layer 20. Preferably corners are slightly roundedbut could be squared off in this perimeter 26. The top layer istypically polyurethane foam, latex foam or some combination thereof. Thedensity is typically between about 2.75 and 4.5 pounds per cubic footwith a density of 2.8 to 3.2 pounds per cubic foot being optimal. Theindentation force deflection is from about ten to twenty. Thickness ismost typically 0.5 to 3.0 inches. This top layer also preferably has asoftness compression modulus of about 1.75 and about 2.35.

The intermediate layer 30 has a geometry similar to that of the toplayer 20. Thus, the intermediate layer 30 includes an upper surface 32opposite a lower surface 34. A perimeter 36 surrounds the upper surface32 and lower surface 34. The intermediate layer 30 is also formed ofpolyurethane or latex foam and is preferably homogeneous between theupper surface 32 and lower surface 34. The intermediate layer 30 islocated below the top layer 20 and with the upper surface 32 preferablybonded to the undersurface 24. Thus, the top layer 20 and intermediatelayer 30 are joined together.

The base layer 40 is a planar layer of polyurethane or latex foam of ahomogeneous character and formed of a unitary mass of foam. The baselayer 40 has a related geometry to the top layer 20 and intermediatelayer 30, but preferably less thick. The base layer 40 extends between adorsal surface 42 opposite a bottom surface 44. A perimeter 46 surroundsthe dorsal surface 42 and bottom surface 44.

The bottom surface 44 preferably includes a notch 48 therein whichfacilitates bending of the base layer 40 and further facilitates bendingof the entire mattress 10, such as when the mattress 10 is placed upon abed frame which is mechanized so that it can raise a head of the user bypivoting near this notch 48. A second notch is typically provided a fewfeet from the opposite end as well. The dorsal surface 42 of the baselayer 40 is preferably bonded to the lower surface 34 of theintermediate layer 30 so that the base layer 40 is joined to the toplayer 20 and intermediate layer 30 to form the mattress 10.

The base layer 40 is preferably thinner than the intermediate layer 30and top layer 20. For instance, in the embodiment depicted in FIGS. 1-3,the top layer 20 and intermediate layer 30 have a similar thickness witheach layer 20, 30 being three inches thick. The base layer 40 in thisembodiment is two inches thick between the dorsal surface 42 and thebottom surface 44. Overall, the base layer 40 thickness can range fromabout 0.5 inch and 5.0 inches. This base layer 40 is typically formed ofpolyurethane foam with a density of about 2.5 to 3.0 pounds per cubicfoot and an optimal density of between about 2.6 and 2.9 pounds percubic foot. The base layer 40 typically has an indentation forcedeflection of about seventy-five to ninety.

Variations on the thickness of the base layer 40 are preferably providedfollowing guidelines calling for the base layer 40 to be half of thethickness of the common layers 20, 30 with a tolerance of between 0.5and one-half inch. Following the narrower tolerance of 0.5 inch, whenthe layers 20, 30 are three inches, the base layer 40 would have athickness of 1.5 inches plus or minus 0.5 inch, so that the base layer40 would have a thickness of between one inch and two inches. Followingthe wider tolerance of 1.0 inch for the base layer 40, the base layer 40could have a thickness of between 0.5 inch and 2.5 inches. In each ofthese embodiments, the base layer 40 has a thickness less than that ofthe top layer 20 and intermediate layer 30. However, a thicker baselayer 40 is another option.

Layers 20, 30, 40 can be formed of polyurethane and/or latex foam, withthe layers 20, 30, 40 preferably not formed of foam having identicalcharacteristics. Rather, the indentation force deflection increases asthe layers 20, 30, 40 progress downward, such that the top layer 20 hasthe lowest indentation force deflection, the intermediate layer 30 hasan intermediate indentation force deflection and the base layer 40 has ahighest indentation force deflection.

Experience has shown that the characteristics of the intermediate layer40 have an important impact on the peak pressure experienced by themattress 10. In particular, the intermediate layer 30 is preferablyprovided with a resilience factor of between forty-five and sixty-fivepercent, such that the intermediate layer 40 can be considered to beformed of foam that is high resilience. A most optimal resilience factorfor the intermediate layer 30 is considered to be fifty-five percent.Furthermore, the intermediate layer 30 preferably has a density ofbetween 2.5 and 3.5 pounds per cubic foot and an IDF of between abouttwenty-five and thirty-five. This intermediate layer also has acompression modulus of about 1.9 to about 2.3. These attributes of theintermediate layer 30 cause the intermediate layer to have the lowaverage pressure and peak pressure readings described above.

EXAMPLE

A mattress was tested having the layer thickness specified herein (threeinch top layer, three inch intermediate layer and two inch bottom layer)and layers of progressively higher IFD. The mattress had an intermediatelayer of high resilience foam with resilience factor of fifty-fivepercent and an IFD in the range of twenty-five to thirty-five, and witha density of 2.5 to 3.5 pounds per cubic foot. While prior artmattresses have high performance in average and maximum pressure, themattress of this test, including the adjusted parameters describedabove, exhibited unexpected and significantly higher performance thanthe prior art. In particular, prior art mattresses disclosed above havebeen tested to show an average pressure of between 23.99 and 24.36, witha maximum or peak pressure of between 91.68 and 95.87 (all measurementsin millimeters of mercury). The mattress of this invention wasindependently tested and found to achieve an average pressure of 17.72with a maximum pressure of 64.42. Thus, a maximum pressure of themattress of this invention is approximately thirty percent less thanprior art mattresses with average pressures also reduced a similaramount. This revolutionary performance can be seen in the context thattheir prior art mattresses disclosed above only exhibited performanceimprovement over earlier prior art in the range of five percent or less.

This reduction in peak and average pressure has significance not only incomfort but in therapeutic environments, such as where pressure sores(also known as “bed sores”) are being remedied or prevented. With suchsignificantly lower peak and average pressures, significantly improvedperformance in therapy of the individual can be expected.

With particular reference to FIGS. 4-8, details of an alternativemattress 110 with lateral support is depicted. This mattress 110 issimilar to the mattress 10 except as described herein. In particular,the mattress 110 includes side supports 50 which bound the perimeters26, 36, 46 of the layers 20, 30, 40. These side supports 50 can beformed as separate pieces as shown, or can be one continuous circuit ofcommon foam material.

The side supports 50 include an upper edge 52 opposite a lower edge 54.The upper edge 52 is preferably coplanar with the top surface 22 of thetop layer 20, but could in other embodiments be somewhat higher (orlower). The lower edge 54 is preferably coplanar with the bottom surface44 of the base layer 40. Thus, the side supports 50 have a heightbetween the lower edge 54 and the upper edge 52 which is similar to adistance between the bottom surface 44 of the base layer 40 and the topsurface 22 of the top layer 20 in the embodiment depicted. In theembodiment depicted in FIGS. 1-3, this thickness is eight inches so thateight inches of height would be provided between the lower edge 54 andthe upper edge 52. In other embodiments, the side supports 50 are higherthan other portions of the mattress 110, such as with a thickness/heighttwo inches higher than the combined layers 20, 30, 40. When the sidesupports 50 are so configured, an inside edge is typically beveled.

The side supports 50 include an inside surface 56 facing inwardly and anoutside surface 58 extending outwardly. The outside surface 58 thusprovides a perimeter for the mattress 110. The inside surface 56 isadjacent the perimeter 26, 36, 46 of the layers 20, 30, 40.

The side supports 50 can be sized so that the inside surface 56 isadjacent the perimeters 26, 36, 46 as one alternative. A secondalternative is to shrink the size of the layers 20, 30, 40 at theirperimeters 26, 36, 46, so that the outside surface 48 of the sidesupports 50 and thus the perimeter of the mattress 110 can be similar tothe perimeter of the mattress 10. Most preferably, the inside surface 56of the side supports 50 is bonded to the perimeter 26, 36, 46 of thelayers 20, 30, 40 so that the mattress 110 has the side supports 50bonded to the other layers 20, 30, 40.

The side supports 50 help to resist any potential for a user to fall offof the top surface 22 of the mattress 10. This is because the sidesupports 50 preferably have high density characteristics and indentationforce deflection characteristics matching that of the base layer 40. Theside supports 50 are thus more resistant to deflection than are the toplayer 20 and intermediate layer 30, and act as a form of “barrier” tolateral movement of a user resting upon the top surface 20 of themattress 10. In the embodiment shown, the side supports 50 completelysurround the mattress 110, but can alternatively be provided only at thelong lateral sides of the mattress 110 and not at the short ends.Preferably, the notch 48 in the base layer 40 continues into the sidesupports 50 so that the side supports 50 can also facilitate bending ofthe mattress 10, such as when on a frame which facilitates such bending.

FIGS. 1-7 illustrate with arrow A the direction with which the mattress10 is typically loaded by having a user resting upon the top layer 20.While the body support is depicted as a mattress 10 sized and shaped toprovide a bed, it could be shaped to fit upon a chair and thus be in theform of a seat cushion, or could have other shapes or other purposes forcarrying a user thereon in a manner which provides comfort andresistance to the development or perpetuation of undesirable conditionssuch as pressure sores.

This disclosure is provided to reveal a preferred embodiment of theinvention and a best mode for practicing the invention. Having thusdescribed the invention in this way, it should be apparent that variousdifferent modifications can be made to the preferred embodiment withoutdeparting from the scope and spirit of this disclosure. When structuresare identified as a means to perform a function, the identification isintended to include all structures which can perform the functionspecified.

What is claimed is: 1: A mattress comprising in combination: a top layerof polyurethane and/or latex foam; an intermediate layer of polyurethaneand/or latex foam bonded to an underside of said top layer; a base layerof polyurethane and/or latex foam bonded to an underside of saidintermediate layer; and wherein said intermediate layer is formed ofhigh resilience foam with a resilience factor of between aboutforty-five percent and sixty-five percent. 2: The mattress of claim 1wherein said intermediate layer has a density of between 2.5 and 3.5pounds per cubic foot. 3: The mattress of claim 1 wherein said layershave a thickness relationship of substantially about equal thickness forsaid top layer and said intermediate layer and said base layer having athickness substantially about half of the intermediate layer. 4: Themattress of claim 3 wherein said base layer thickness has a tolerance ofplus or minus 0.5 to 1 inches. 5: The mattress of claim 1 wherein saidintermediate layer is formed of high resilience foam with a resiliencefactor of about fifty-five percent. 6: The mattress of claim 1 whereinsaid intermediate layer is formed of a foam having an indentation forcedeflection (IFD) of between twenty-five and thirty-five. 7: The mattressof claim 1 wherein said top layer is approximately three inches thick,said intermediate layer is approximately three inches thick and saidbottom layer is approximately two inches thick. 8: The mattress of claim1 wherein side supports bound lateral edges of said top layer, saidintermediate layer and said base layer, said side supports formed ofpolyurethane and/or latex foam extending from a bottom surface of saidbase layer to a top surface of said top layer. 9: The mattress of claim8 wherein said side supports are formed from a common foam with saidbase layer, and with said side supports bonded to each of said toplayer, said intermediate layer and said base layer. 10: A low peakpressure mattress, comprising in combination: a top layer ofpolyurethane and/or latex foam; an intermediate layer of polyurethaneand/or latex foam; a base layer of polyurethane and/or latex foam; andwherein said intermediate layer is formed of high resilience foam with aresilience factor of between forty-five percent and sixty-five percent.11: The low peak pressure mattress of claim 10 wherein said intermediatelayer has a resilience factor of about fifty-five percent. 12: The lowpeak pressure mattress of claim 11 wherein said intermediate layer has adensity of between 2.5 pounds per cubic foot and 3.5 pounds per cubicfoot. 13: The low peak pressure mattress of claim 12 wherein said toplayer, said intermediate layer and said base layer are each bondedtogether. 14: The low peak pressure mattress of claim 13 wherein saidtop layer is approximately three inches thick, said intermediate layeris approximately three inches thick and said bottom layer isapproximately two inches thick. 15: The low peak pressure mattress ofclaim 14 wherein side supports bound lateral edges of said top layer,said intermediate layer and said base layer, said side supports formedof polyurethane and/or latex foam extending from a bottom surface ofsaid base layer to a top surface of said top layer. 16: The low peakpressure mattress of claim 15 wherein said side supports are formed froma common foam with said base layer, and with said side supports bondedto each of said top layer, said intermediate layer and said base layer.17: The low peak pressure mattress of claim 15 wherein said intermediatelayer has an IFD of between about twenty-five and thirty-five.